if A = i -3j + 4k , B = 6i + 4j - 8k , C=5i + 2j + 5k and a vector R satisfies RXB = CXB, R.A = 0 , then |B|/|R-C| is
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if A = i -3j + 4k , B = 6i + 4j - 8k , C=5i + 2j + 5k and a vector R satisfies RXB = CXB, R.A = 0 , then |B|/|R-C| is